Retirement Benefit Plans - Roll Forward of Defined Benefit Pension Plan Obligationas and Assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2016	Sep. 30, 2015
Benefit obligations:
Benefit obligations at beginning of year	$ 27,685	$ 26,140
Transfer in	0	465
Service cost	280	148
Interest cost	1,017	978
Actuarial loss	2,405	1,328
Benefits paid	(1,659)	(1,377)
Currency translation	3	3
Plan assets at end of year	29,731	27,685
Plan assets:
Plan assets at beginning of year	20,896	22,110
Actual return on plan assets	2,061	117
Employer contributions	46	46
Benefits paid	(1,659)	(1,377)
Plan assets at end of year	$ 21,344	$ 20,896